|Image from Thirsties|
The Thirsties Duo AIO size 1, was, in essence, a newborn diaper for my girl. I used them on her on the smallest snap-down at one week old! (8 lbs.-ish) After 2 weeks old, there was no need to snap it down anymore. The company says it's meant to fit from 6-18 lbs., but we certainly didn't get close to that!
My friend had warned me she had absorbency issues with these, so I did what I had advised her to do: stuff the "tunnel" with a thin hemp booster. We did this at around 10 lbs. and it worked for a while. Also, a Ragababe liner fit in the tunnel perfectly!
The tunnel was a novel idea, but it didn't always dry thoroughly and needed some inside-out airing.
By just over 11 lbs. (just over 1 month), Miss C. was maxing out the absorbency even with a booster, and they were getting snug. Time to retire! Around this time we brought out some of our one-size diapers.
This was great to have on hand (and in such quantity) so I could have all AIOs, and they did their job while they fit. I didn't like having to stuff them with an extra loose piece, though -- because then it's hardly more than a pocket. Anyway, now Thirsties makes a One-Size AIO (which I will review in the future!) and that design worked a lot better.